Hermetically sealed or sealable connectors are well known in the art. Exemplary hermetic connectors are described, for example, in U.S. Pat. Nos. 5,110,307, 6,932,644, 7,144,274 and 7,300,310. These patents relate, generally, to connectors having an outer connector shell or body with an interior insert having apertures sized to receive connector pin/socket structures. The connector pins are held in place and hermetically sealed within the apertures using a glass or ceramic material.
FIG. 1 illustrates a schematic cross-sectional view of a conventional (prior art), multi-pin RF feed-through connector of the type described above. Connector 100 comprises an outer support shell 110 having mounting bores 111 for attaching to a support structure of a companion external connector having an arrangement of pins that mate with and are inserted into sockets 112 for connection with associated conductive pins 115. In this type of connector, an insert 120 made, for example, from a metallic material such as stainless steel, is bonded to the outer support shell, such as at solder joint 113. Pins 115 and corresponding sockets 112 are generally mounted through cylindrical bores 114 provided in insert 120 and hermetically sealed in insert 120 using a dielectric material such as glass 118 or ceramic materials.
Because the different metallic materials comprising the connector shell and insert, and glass materials, have different thermal properties, e.g. different thermal expansion properties, the performance of connectors constructed in this fashion tends to degrade over periods of thermal cycling. Additional layers and components, or multi-layer structures, may be used to facilitate bonding of materials having similar thermal properties to one another to improve the durability and performance of the connector. The U.S. patents cited above describe connectors of this type.
Electronics packages have been produced using multilayer ceramics processes in which ceramic powders are prepared and cast as a tape. Metal powders are prepared as pastes and applied, generally by screen printing, on the green (or on a fired) ceramic tape. Individual components may be arranged in arrays on a multi-layer assembly for processing as a single unit and separated during or following processing. Via holes, edge castellations and cavities may be punched in the tape and then coated, or filled, with a refractory metal paste. These cavities provide electrical interconnections between layers and provide conductive pathways from one side to the other. The layers are stacked and laminated, and individual components may be cut or punched out, or the array may be scored to facilitate post-firing operations. The stacked, laminated structure is then sintered, or co-fired, at generally high temperatures in a controlled atmosphere environment. Ceramic packages may be plated or metalized to provide conductive areas for attachment of metal components by brazing. Metal pins, seal rings and heat sinks may be attached to metalized portions of ceramics packages by brazing to form hermetic joints. Alumina is a commonly used ceramic material for multi-layer packages because of its high strength, good thermal conductivity, hermeticity and desirable electrical properties.